The authenticity of a user interacting with the website may be determined in a number of ways, such as a challenge-response test that only the intended user is likely to be able to answer. This may prevent unauthorized use of a computing resource by another user or by an automated computing algorithm. One type of challenge question aimed at automated computing algorithms is called a CAPTCHA, which is an acronym for “Completely Automated Turing Test To Tell Computers and Humans Apart.” A common type of CAPTCHA requires the user to type letters or numbers from a distorted image that is difficult for a computing algorithm to interpret but relatively easy for a human. Requiring a user to read distorted text for authentication prevents automatic systems from connecting to a website without user intervention. Other forms of CAPTCHAs may require the user to ask a common sense question, for example, “in the English alphabet, what letter comes after D.” However, existing CAPTCHA mechanisms can be defeated by a practice known as “CAPTCHA farming,” wherein an automated algorithm temporarily diverts the CAPTCHA question to a human user to solve the CAPTCHA question and then returns to its illegitimate purpose. If cheap human labor can be utilized, the existing CAPTCHA mechanisms can be rendered completely ineffective.